Vehicle stability systems may engage anti-lock braking systems (ABS) and/or electronically-controlled limited-slip differentials (ELSDs) to improve vehicle traction and stability. For example, when a vehicle attempts to accelerate or climb on a split-mu, low-high friction surface, the ABS and the ELSD may be controlled to send more driving torque to the driven wheel so the vehicle can maintain longitudinal motion, sending more traction torque to the higher friction wheel. However, at higher vehicle speeds, yaw stability must be carefully controlled, particularly near the vehicle's stability limit, to prevent undesired yaw motion so the vehicle does not deviate laterally from the driver's intended direction.
Generally, yaw control in the stability system can be conducted by comparing a desired vehicle yaw rate with a measured vehicle yaw rate obtained from an on-board Inertia Measurement Unit (IMU) sensor. The desired yaw rate can be calculated in real time using a vehicle model calibrated with the desired vehicle handling, characteristics. When the measured yaw rate differs from the desired yaw rate, a yaw controller is triggered to correct the yaw rate and reduce the difference between the measured and desired values.
A fast response time is desirable to achieve proper vehicle yaw control. However, actuator and sensor delay can significantly delay corrections to an input in the yaw controller and therefore delay engagement and disengagement of the ABS and/or the ELSD for stability control. This delay can reduce the overall effectiveness of the vehicle yaw control system. Thus, it is important to minimize delays in both engaging and disengaging the vehicle stability system.
There is a desire for a yaw control that has a fast response time to minimize response time delay in a vehicle stability system.